Ecology Part 3

Earth’s human population continues to grow.

• Earth’s human carrying capacity is unknown.

• Technology has helped to increase Earth’s carrying capacity.

– gas-powered farm equipment– medical advancements

The growing human population exerts pressure on Earth’s natural resources.

• Nonrenewable resources are used faster than they form.– coal– oil

• Renewable resources cannot be used up or can replenish themselves over time.– wind– water– sunlight

• Growing use of nonrenewable resources may lead to a crisis.

• Resources must be properly managed.

• An ecological footprint is the amount of land needed to support a person.

• The land must produce and maintain enough– food and water– shelter– energy– waste

• Several factors affect the size of the ecological footprint.– amount and efficiency of resource use – amount and toxicity of waste produced

Pollutants accumulate in the air. • Pollution is any undesirable

factor added to the air, water, or soil.

• Smog is one type of air pollution.– sunlight interacts with

pollutants in the air– pollutants produced by fossil

fuel emissions– made of particulates and

ground-level ozone

• Smog can be harmful to human health.• Acid rain is caused by fossil fuel emissions.

– produced when pollutants in the water cycle cause rain pH to drop

– can lower the pH of a lake or stream– can harm trees

Air pollution is changing Earth’s biosphere.

• The levels of atmospheric carbon dioxide rise and fall over time.• High levels of carbon dioxide are typical of Earth’s warmer

periods.

• The greenhouse effect slows the release of energy from Earth’s atmosphere.1.sunlight penetrates Earth’s atmosphere2.energy is absorbed and reradiated as heat3.greenhouse gases absorb longer wavelengths4.Greenhouse

gas moleculesrereleaseinfraredradiation

methane (CH4) water (H2O)

carbon dioxide(CO2)

• Global warming refers to the trend of increasing global temperatures.

North Pole

Water pollution affects ecosystems.

• Pollution can put entire freshwater ecosystems at risk. • Examples of water pollution include: raw sewage, chemical

contaminants, trash, detergents and fertilizers used in fields.

• Indicator species provide a sign of an ecosystem’s health.– Examples include:– amphibians

– top predators

Biomagnification causes accumulation of toxins in the food chain.

• Pollutants can move up the food chain.– predators eat contaminated

prey– pollution accumulates at each

stage of the food chain• Top consumers, including

humans, are most affected.

Preserving biodiversity is important to the future of the biosphere.

• The loss of biodiversity has long-term effects.– loss of medical and technological advances– extinction of species– loss of ecosystem stability

Loss of habitat eliminates species. • Habitat fragmentation prevents an organism from

accessing its entire home range.– occurs when a barrier forms within the habitat– often caused by human development

• Habitat corridors are a solution to the problem.– corridors can be road overpasses or underpasses– allow species to move between different areas of habitat

Introduced species can disrupt stable relationships in an ecosystem.

• An introduced species is one that is brought to an ecosystem by humans.– accidental– purposeful

• Invasive speciescan have anenvironmentaland economicimpact.

• Invasive species often push out native species.– Burmese python (Florida Everglades)

• Invasive species often push out native species.– mice (Australia)

• Invasive species often push out native species.– kudzu (southeastern United States)

Sustainable development manages resources for present and future generations.

• Sustainable development meets needs without hurting future generations.– Industry examples:

• Forestry• Fishing• hunting

Protecting Earth’s resources helps protect our future.

• The Environmental Protection Agency (EPA) was created in 1970.

• The EPA develops policies and regulations to protect the environment.

• Legislation helps to protect the environment and endangered species.– Clean Air Act– Clean Water Act– Endangered Species Act

Conservation practices focus on a few species but benefit entire ecosystems.

• The Endangered Species Act works to protect individual species from extinction.

• A listed species is often called an umbrella species.

– Species’ habitat that must be protected

– other species are protected because they share the ecosystem

• There are several ways that people can help protect the environment.– control population growth– develop sustainable technology and practices– protect and maintain ecosystems